1. Field of the Invention
The present invention relates to a leveler for stretcher-leveling of a metal strip or sheet and including a frame, at least two roller leveling units supported in the frame and arranged, respectively, above and below a rolled stock, and a guide for displacing the roller leveling units between their operational position and their roller maintenance and exchange position, with each of the roller leveling units including a roller magazine including at least one leveling roller rotatable about its longitudinal axis, and an adjusting element for displacing the roller leveling unit toward and away from the rolled stock.
2. Description of the Prior Art
As is known, during stretcher leveling of metal sheet material or strips in order to obtain sheet material and strips with a high flatness and a minimal residual internal stress, the sheet material or strips is (are) fed through a leveling clearance formed by upper and lower leveling rollers and corresponding to the cross-section of the sheet material or the strip.
European Publication EP 0 446 130 B1 discloses a leveler for stretcher-leveling a metal strip with at least two roller leveling units offset in the displacement direction of the strip and arranged above and below the strip. The leveler further includes guide and control means for displacing both units vertically between an operational position and an idle position in which the roller leveling units are spaced from the strip. Each roller leveling unit includes a chassis or a roller magazine including at least one leveling roller rotatable about its axis. For maintenance or for changing the rollers, both roller leveling units are displaced, transverse to the strip displacement direction, by a changing device sidewise of the leveler frame. When the lower roller leveling unit or the lower leveling roller is subjected to a maintenance work or is being replaced, the roller(s) of the upper roller leveling unit are accessible only with much difficulties. In order to improve the accessibility of the upper rollers, it is suggested to rotate the entire upper roller leveling unit about its longitudinal axis by 180xc2x0 to bring the rollers into an upper position.
To bring the roller(s) into the upper position, it is suggested to pivotally mount the chassis on two opposite aligned journals which are supported in opposite support elements. The journals define a horizontal axis about which the entire upper roller leveling unit pivots between an operational position, in which the leveling roller(s) face(s) downwardly, and a maintenance and exchange position in which the roller(s) face(s) upwardly.
The solution suggested in EP 0 446 130 B1 is rather expensive as means needs to be provided for rotating the entire upper roller leveling unit to insure access to the leveling roller(s) of the upper unit for maintenance and exchange purposes.
Accordingly, an object of the present invention is to provide a leveler of the type described above in which the roller(s) of the upper leveling unit could be made accessible for maintenance and exchange without the need to rotate the entire upper roller leveling unit about its horizontal axis.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a leveler in which the roller magazine of the upper roller leveling unit has a support unit for supporting the leveling roller and pivotally arranged on a run-in side or run-out side of the roller magazine for pivotal movement between operational and maintenance and exchange positions.
The advantage of the solution according to the present invention consists in that only the roller(s) of the upper roller leveling unit and their support means need to be rotated to bring the roller(s) in its (their) maintenance and exchange position. As the present invention is directed primarily to the upper roller leveling unit, the roller support unit is arranged beneath the roller magazine. The pivot angle between the operational position and the pivoted position is so selected that the access to the roller(s) for maintenance and exchange purposes is insured.
Accordingly to an advantageous embodiment of the present invention the support unit includes at least two roller housings for supporting opposite ends of the leveling roller, two brackets for supporting the at least two roller housings and pivotally arranged on the roller magazine, and fastening means, preferably screw means, for releasably secure the brackets at their side opposite their pivot points to the roller magazine for retaining the support unit in the operational position.
In order to improve handling of the upper roller leveling unit, there are provided on the end side of the roller magazine, i.e., on the side of the roller magazine extending parallel to the strip displacement direction, at least two spring elements cooperating with respective brackets and dimensioned in such a way that a total gravity force of the housings, including the respective leveling rollers, and the brackets is compensated by spring forces. The spring elements can be formed as gas springs, hydraulic springs, or mechanical springs. When a gas pressure spring is used, the rod head is displaced past its dead point during the pivotal movement, which insures the support unit in its maintenance and exchange position against a possible rebound.
Generally, a manual pivoting of the support unit is contemplated. However, it is also possible to use different manipulators connectable with the support unit for pivoting same.
For synchronization of the pivotal movement of both roller housings, there is provided a stirrup which serves as a handle, extends along the longitudinal axis of the roller magazine, i.e., transverse to the strip displacement direction, and is connected, at its opposite ends, with the two brackets, which are located on the drive and operator""s side of the roller magazine.
Generally, the pivotal movement is effected in the idle position of the roller leveling unit, i.e., in the position in which the roller leveling unit is spaced from the strip. However, for security and handling reasons, there is provided guide means for displacing the roller leveling units horizontally toward the strip delivery place and to the maintenance and exchange position which is located adjacent to the leveler frame.
The present invention also includes a system for stretcher-leveling of a metal strip, in particular, a cold-rolled or hot-rolled thin slab and which includes a plurality of levelers described above, or a single leveler with a plurality of roller leveling units, e.g., six, together with control means controlling the strip displacement.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.